Mr Fox, of Park Road, New Barnet, Hertforshire, who is alleged to be an “underworld enforcer”, turned up uninvited at Mr Hall’s family home in Lauriston Road, Wimbledon, on February 29.

Mr Hall said Mr Fox’s unsolicited visit to their home while builders were at work was “very, very upsetting”.

He claimed to be acting for a client who alleged a company, part-owned by Mr Hall, owed £67,000.

Although his wife was not there when Mr Fox called, Mr Hall – who denies owing anything – told Judge Richard Seymour QC that the incident had been “very, very upsetting” for her.

Mr Hall is now fighting in the High Court for damages and an injunction against the debt collector on grounds that he has been “harassing” him over the alleged debt with “menacing threats”.

On Monday, Mr Hall, in the witness box, told Mr Fox, who is representing himself: “You were putting considerable pressure on me and my family.

“My wife’s hair has nearly gone white since you walked in our house... My understanding is you are an underworld enforcer and you threaten people in order to get money.”

In a statement about the visit Mr Hall said: “The defendant intimidated the builders who were working on site and took it upon himself to walk around the premises, while uttering further threats of
violence to the point that one of the contractors decided to leave, in fear of their own personal safety.”

Mr Hall wants an injunction preventing Mr Fox coming within 100 yards of his home in Wimbledon or his other properties in Chelsea Harbour, Market Place, central London, and his offices in Arlington
Street, Piccadilly.

“Unannounced, he attended Mr Hall’s offices and, on occasion, his home, for the purpose of applying pressure one way or another to ensure that he pay the sums of money that Mr Fox suggests is his
due and owing and Mr Hall says is not.

“We say the course of conduct is such that it amounts to harassment. There is no proper excuse for what has been going on.”